The present disclosure relates generally to information handling systems, and more particularly to a differential trace pair system in an information handling system.
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Information handling systems such as, for example, switches, servers, and/or other information handling systems include circuit boards with communication traces that are provided in those circuit boards and connected to different subsystems in order to provide for the transmission of information between the subsystems. For example, a differential trace pair may be provided between a transmitter subsystem and a receiver subsystem in the switch or server (or between different switches and/or servers) to transmit and receive information. In some situations, the differential trace pair may couple to the transmitter subsystem and/or the receiver subsystem after being routed through a pin field such as, for example, a Ball Grid Array (BGA) pin field. Because the pins and associated vias in the circuit board that provide the BGA pin field are relatively closely spaced, the differential trace pair may require a “neck-down” region that includes a change in width of the differential trace pair that allows the differential trace pair to be routed between the pins/vias that are included in the BGA pin field. The provision of such neck-down regions in a differential trace pair can introduce some issues.
As the transmission of information using differential trace pairs is performed at higher and higher speeds, the widths of the traces in the differential trace pair must be increased in order to address losses. For example, for a 10 G transmission rate, the width and spacing of the traces in a differential trace pair is typically around 4-5.5 mils, while for a 25 G transmission rate with similar losses, the width and spacing of the traces in the differential trace pair is typically around 8 mils. When a differential trace pair is used to transmit information at a 25 G transmission rate and must also route through a BGA pin field, the spacing of pins/vias in the BGA pin field will not allow the width and spacing of the differential trace pair discussed above. Conventional solutions attempt to solve this problem by narrowing the traces in the differential trace pair. However, the manufacturing of such thinner differential traces raises several issues. For example, current manufacturing processes present difficulties in producing such thin traces. Furthermore, providing such differential traces at those widths can cause high impedance variations in the differential trace pair that, while not causing issues at 10 G transmission rates, can cause problems at 25 G transmission rates.
Accordingly, it would be desirable to provide an improved neck-down region in a differential trace pair.